Quote:
Originally Posted by PSALM19.1
Thanks very much for that response...yes, seems as though there are many variables with refractors! I certainly (at this stage anyway) am not interested in photography (my daughter did snap a few very good photos of the moon through the eyepiece of my Dob however!); I just like studying planets and deep space objects...I guess my confusion is that if it's 8" of Dob apeture vs, say, 5" in a large refractor, how can the refractor give a better view (again; no photography here, just straight viewing) when the Dob is receiving so much more light? All a learning curve...but I am keen!
|
Shaun
Planets are bright objects so gathering light is not really the issue. Refractors have no central obstruction that Newtonians have, and that improves contrast, which can be helpful with planets. Also refractors can have fairly long focal lengths for their aperture and can handle reasonably high power. As planets are small, more power can be valuable.
Of course, refractors can be subject to colour fringing which was the specific problem the Newt was invented to solve.
From all this you can gather that there is no perfect scope, all involve some compromise and have strengths and weaknesses.
My main argument for getting a dob is that there are '000s of objects visible with even a small dob, while there are only 7 planets (and only 3 of those are really worth observing much!), and dobs still make reasonable planetary scopes.
Malcolm